WASHINGTON — President Donald Trump is taking the unusual step of weighing in publicly ahead of a foreign presidential election, predicting that the latest attack in Paris will have a “big effect” on voters there.

“Another terrorist attack in Paris. The people of France will not take much more of this. Will have a big effect on presidential election!” he tweeted.

On Thursday, an attacker in Paris used an automatic weapon to shoot officers in the center of the Champs-Elysees. One...